In a substrate processing apparatus, a chamber lid and a cup are located at a first position, a cup side wall and a liquid receiving side wall overlap each other in a radial direction, and a guard is supported by a liquid receiving side wall. When the chamber lid and the cup move to a second position that is above the first position, the guard moves upward while being suspended from the cup side wall. When the chamber lid and the cup are located at the second position, the lower end of the cup side wall is located above the upper end of the liquid receiving side wall, and the guard covers a gap between the lower end of the cup side wall and the upper end of the liquid receiving side wall.